I have a 2016 1.6TDI DSG Octavia Estate. 130,000 miles and I've owned the car for 6 years. Fuel consumption recently has noticably got a lot worse. I know it always varies a bit and I expect a bit worse in winter, but it has reached a low point I've never seen before in 6 years of ownership. Typically, a full tank gets me 500 - 550 miles before it needs refilling (I just got to 600 once). But my latest tank full has only lasted just over 400 miles. That's at least 20% worse than normal. My driving has been completely normal. On a recent motorway run at a steady 70mph, it reported average consumption of 52 - I would normally expect to see at least 60. There are no symptoms of any problems, no error lights or poor running or anything. Perhaps there is a slight smokey smell occasionally, like a sooty exhaust smell - but there is no exhaust smoke or anything. Nothing abnornal when I look under the bonnet either. The oil was last changed about 500 miles ago. Air filter and fuel filter recently changed too.

Any suggestions? Where should I start looking? Should I take it to a diesel specialist for an injector check and tune-up etc?

Any similar experiences or suggestions gratefully received.

Thanks - Joe

DPF not regenerating and getting blocked? Check fault codes with a simple reader to find out what's wrong and get a good indy VAG workshop to have a proper look.

Im not a diesel expert and you've owned for 6 consecutive years, so have been through winters before....

Don't under estimate though, higher current draw, lights, cold starts. Does translate into more fuel. As well as that ive seen quite a few posts before about the diesel fuel composition change over winter months. So I don't have first hand knowledge of what % impact that could make and to expect.

Putting all that to one side for a moment. If you want to check things, alternator, air con pulleys, check bearings not on way out. Belt tensioner as well.

Lift wheels. Check for binding brakes, front and rear.

Check tyre pressures.

That would cover some of the physical things.

Might be worth trying a tank of premium diesel to clean out the fuel line and injectors, or trying fuel from a different place.

Checking tyre pressure will help, ensure it's on the low load pressure unless you are towing or carrying a lot of weight.

Is it re-generating more than normal?

There should be no smokey diesel smell.

Could be a sensor issue or injector over fuelling but all guess work.

Take it to a specialist, extra diesel "could" be getting into the oil, so worth changing that after you have it fixed.

Thanks for all your replies. I've found the answer, a little embarrassing, but I've added it here in case it helps anyone else in future.

I took the vehicle to a specialist as suggested. They discovered that the oil filler cap was not properly secured, which was causing a crank-case air leak. This caused an extra rich mixture and clogged up the dpf. They re-cycled the dpf, which cleared it up - and the problem was solved. The smokey smell was either a bit of mist escaping the crank-case or a bit of oil splash on the exhaust. This cost me an investigation fee of £108. I guess I incorrectly re-fitted the cap at the last oil-change, about a thousand miles ago. You live and learn.

Joe

Edited 11 February11 Feb by JJC77